In this paper a new detailed simulation framework of the UHF RFID Vehicle Identification System based on EPC Class1 Gen2 modeling is described. The simulation includes protocol settings, antennas parameters and propagation media conditions. Propagation analysis considers Doppler shift to compute path loss of moving tags properly. The estimation of an inventory round duration, the rounds number and vehicles and tags identification probabilities are presented. The results of simulation coincide with the experiment results involving the city buses. The framework is written in Python and C++ languages and makes use of OMNeT++ discrete-event simulator.